Security Vulnerabilities fixed in Firefox 98 — Mozilla

When resizing a popup after requesting fullscreen access, the popup would not display the fullscreen notification.
If an attacker could control the contents of an iframe sandboxed with allow-popups but not allow-scripts, they were able to craft a link that, when clicked, would lead to JavaScript execution in violation of the sandbox.
When installing an add-on, Firefox verified the signature before prompting the user; but while the user was confirming the prompt, the underlying add-on file could have been modified and Firefox would not have noticed.
An attacker could have caused a use-after-free by forcing a text reflow in an SVG object leading to a potentially exploitable crash.
While the text displayed in Autofill tooltips cannot be directly read by JavaScript, the text was rendered using page fonts. Side-channel attacks on the text by using specially crafted fonts could have lead to this text being inferred by the webpage.
In unusual circumstances, an individual thread may outlive the thread’s manager during shutdown. This could have led to a use-after-free causing a potentially exploitable crash.
Mozilla developers Kershaw Chang, Ryan VanderMeulen, and Randell Jesup reported memory safety bugs present in Firefox 97. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.